This invention relates generally to the grinding or sharpening of cutting tools, particularly of relatively elongate, straight-edged cutting tools such as knives for use on veneer lathes and veneer slicers. More particularly, the invention pertains to a method of, and apparatus for, finish-grinding the edges of such cutting tools to an extent known as superfinishing in the art, after they have been rough-ground by conventional machines.
The superfinishing of the cutting tools of the class under consideration has long relied upon the dexterity of veteran workers using flat abrasive stones. Being based on empirical knowledge, such hand finishing requires utmost skill which is attainable only after years and years of practice. The operation itself, moreover, is very timeconsuming and uneconomical.
Recently, machine finishing has been introduced which employs a mechanical spring for pressing a superfine grinding wheel against the work. Preparatory to grinding, the spring is stressed to an extent necessary to enable the wheel to grind the work to a desired depth. The use of a spring is objectionable, however, because it does not necessarily urge the grinding wheel against the work under constant pressure; rather, the spring tends to impart vibrations to the grinding wheel, resulting in the fine skipping of the wheel over the work as the wheel travels longitudinally of the work. The spring-biased grinding wheel may thus fail to grind the work to a desired degree of superfine finish and, in the worst case, may even destroy its cutting edge.
Finish grinding has long been thought of as an indispensible, but somewhat minor, supplement to rough grinding. It has therefore been practiced to use a rough-grinding machine for finish grinding, merely by changing the grinding wheels to finer ones. This practice is objectionable not only because of the poor finish obtained, but also because the grinding wheel or wheels are set at fixed angles with respect to the work. Such fixed-angle wheels do not lend themselves to use for double-, triple- or other multiple-taper grinding of the work for the provision of more durable cutting edges. For these reasons the advent of exclusive superfinishing machines has long been awaited in the woodworking industry.